text: #ifndef _ARCH_POWERPC_UACCESS_H
  #define _ARCH_POWERPC_UACCESS_H
  
  #ifdef __KERNEL__
  #ifndef __ASSEMBLY__
  
  #include <linux/sched.h>
  #include <linux/errno.h>
  #include <asm/asm-compat.h>
  #include <asm/processor.h>
  #include <asm/page.h>
  
  #define VERIFY_READ	0
  #define VERIFY_WRITE	1
  
  /*
   * The fs value determines whether argument validity checking should be
   * performed or not.  If get_fs() == USER_DS, checking is performed, with
   * get_fs() == KERNEL_DS, checking is bypassed.
   *
   * For historical reasons, these macros are grossly misnamed.
   *
   * The fs/ds values are now the highest legal address in the "segment".
   * This simplifies the checking in the routines below.
   */
  
  #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  
  #define KERNEL_DS	MAKE_MM_SEG(~0UL)
  #ifdef __powerpc64__
  /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
  #define USER_DS		MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
  #else
  #define USER_DS		MAKE_MM_SEG(TASK_SIZE - 1)
  #endif
  
  #define get_ds()	(KERNEL_DS)
  #define get_fs()	(current->thread.fs)
  #define set_fs(val)	(current->thread.fs = (val))
  
  #define segment_eq(a, b)	((a).seg == (b).seg)
  
  #define user_addr_max()	(get_fs().seg)
  
  #ifdef __powerpc64__
  /*
   * This check is sufficient because there is a large enough
   * gap between user addresses and the kernel addresses
   */
  #define __access_ok(addr, size, segment)	\
  	(((addr) <= (segment).seg) && ((size) <= (segment).seg))
  
  #else
  
  #define __access_ok(addr, size, segment)	\
  	(((addr) <= (segment).seg) &&		\
  	 (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))
  
  #endif
  
  #define access_ok(type, addr, size)		\
  	(__chk_user_ptr(addr),			\
  	 __access_ok((__force unsigned long)(addr), (size), get_fs()))
  
  /*
   * The exception table consists of pairs of addresses: the first is the
   * address of an instruction that is allowed to fault, and the second is
   * the address at which the program should continue.  No registers are
   * modified, so it is entirely up to the continuation code to figure out
   * what to do.
   *
   * All the routines below use bits of fixup code that are out of line
   * with the main instruction path.  This means when everything is well,
   * we don't even have to jump over them.  Further, they do not intrude
   * on our cache or tlb entries.
   */
  
  struct exception_table_entry {
  	unsigned long insn;
  	unsigned long fixup;
  };
  
  /*
   * These are the main single-value transfer routines.  They automatically
   * use the right size if we just have the right pointer type.
   *
   * This gets kind of ugly. We want to return _two_ values in "get_user()"
   * and yet we don't want to do any pointers, because that is too much
   * of a performance impact. Thus we have a few rather ugly macros here,
   * and hide all the ugliness from the user.
   *
   * The "__xxx" versions of the user access functions are versions that
   * do not verify the address space, that must have been done previously
   * with a separate "access_ok()" call (this is used when we do multiple
   * accesses to the same area of user memory).
   *
   * As we use the same address space for kernel and user data on the
   * PowerPC, we can just do these as direct assignments.  (Of course, the
   * exception handling means that it's no longer "just"...)
   *
   */
  #define get_user(x, ptr) \
  	__get_user_check((x), (ptr), sizeof(*(ptr)))
  #define put_user(x, ptr) \
  	__put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  
  #define __get_user(x, ptr) \
  	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
  #define __put_user(x, ptr) \
  	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  
  #define __get_user_inatomic(x, ptr) \
  	__get_user_nosleep((x), (ptr), sizeof(*(ptr)))
  #define __put_user_inatomic(x, ptr) \
  	__put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  
  #define __get_user_unaligned __get_user
  #define __put_user_unaligned __put_user
  
  extern long __put_user_bad(void);
  
  /*
   * We don't tell gcc that we are accessing memory, but this is OK
   * because we do not write to any memory gcc knows about, so there
   * are no aliasing issues.
   */
  #define __put_user_asm(x, addr, err, op)			\
  	__asm__ __volatile__(					\
  		"1:	" op " %1,0(%2)	# put_user\n"		\
  		"2:\n"						\
  		".section .fixup,\"ax\"\n"			\
  		"3:	li %0,%3\n"				\
  		"	b 2b\n"					\
  		".previous\n"					\
  		".section __ex_table,\"a\"\n"			\
  			PPC_LONG_ALIGN "\n"			\
  			PPC_LONG "1b,3b\n"			\
  		".previous"					\
  		: "=r" (err)					\
  		: "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
  
  #ifdef __powerpc64__
  #define __put_user_asm2(x, ptr, retval)				\
  	  __put_user_asm(x, ptr, retval, "std")
  #else /* __powerpc64__ */
  #define __put_user_asm2(x, addr, err)				\
  	__asm__ __volatile__(					\
  		"1:	stw %1,0(%2)\n"				\
  		"2:	stw %1+1,4(%2)\n"			\
  		"3:\n"						\
  		".section .fixup,\"ax\"\n"			\
  		"4:	li %0,%3\n"				\
  		"	b 3b\n"					\
  		".previous\n"					\
  		".section __ex_table,\"a\"\n"			\
  			PPC_LONG_ALIGN "\n"			\
  			PPC_LONG "1b,4b\n"			\
  			PPC_LONG "2b,4b\n"			\
  		".previous"					\
  		: "=r" (err)					\
  		: "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
  #endif /* __powerpc64__ */
  
  #define __put_user_size(x, ptr, size, retval)			\
  do {								\
  	retval = 0;						\
  	switch (size) {						\
  	  case 1: __put_user_asm(x, ptr, retval, "stb"); break;	\
  	  case 2: __put_user_asm(x, ptr, retval, "sth"); break;	\
  	  case 4: __put_user_asm(x, ptr, retval, "stw"); break;	\
  	  case 8: __put_user_asm2(x, ptr, retval); break;	\
  	  default: __put_user_bad();				\
  	}							\
  } while (0)
  
  #define __put_user_nocheck(x, ptr, size)			\
  ({								\
  	long __pu_err;						\
  	__typeof__(*(ptr)) __user *__pu_addr = (ptr);		\
  	if (!is_kernel_addr((unsigned long)__pu_addr))		\
  		might_fault();					\
  	__chk_user_ptr(ptr);					\
  	__put_user_size((x), __pu_addr, (size), __pu_err);	\
  	__pu_err;						\
  })
  
  #define __put_user_check(x, ptr, size)					\
  ({									\
  	long __pu_err = -EFAULT;					\
  	__typeof__(*(ptr)) __user *__pu_addr = (ptr);			\
  	might_fault();							\
  	if (access_ok(VERIFY_WRITE, __pu_addr, size))			\
  		__put_user_size((x), __pu_addr, (size), __pu_err);	\
  	__pu_err;							\
  })
  
  #define __put_user_nosleep(x, ptr, size)			\
  ({								\
  	long __pu_err;						\
  	__typeof__(*(ptr)) __user *__pu_addr = (ptr);		\
  	__chk_user_ptr(ptr);					\
  	__put_user_size((x), __pu_addr, (size), __pu_err);	\
  	__pu_err;						\
  })
  
  
  extern long __get_user_bad(void);
  
  #define __get_user_asm(x, addr, err, op)		\
  	__asm__ __volatile__(				\
  		"1:	"op" %1,0(%2)	# get_user\n"	\
  		"2:\n"					\
  		".section .fixup,\"ax\"\n"		\
  		"3:	li %0,%3\n"			\
  		"	li %1,0\n"			\
  		"	b 2b\n"				\
  		".previous\n"				\
  		".section __ex_table,\"a\"\n"		\
  			PPC_LONG_ALIGN "\n"		\
  			PPC_LONG "1b,3b\n"		\
  		".previous"				\
  		: "=r" (err), "=r" (x)			\
  		: "b" (addr), "i" (-EFAULT), "0" (err))
  
  #ifdef __powerpc64__
  #define __get_user_asm2(x, addr, err)			\
  	__get_user_asm(x, addr, err, "ld")
  #else /* __powerpc64__ */
  #define __get_user_asm2(x, addr, err)			\
  	__asm__ __volatile__(				\
  		"1:	lwz %1,0(%2)\n"			\
  		"2:	lwz %1+1,4(%2)\n"		\
  		"3:\n"					\
  		".section .fixup,\"ax\"\n"		\
  		"4:	li %0,%3\n"			\
  		"	li %1,0\n"			\
  		"	li %1+1,0\n"			\
  		"	b 3b\n"				\
  		".previous\n"				\
  		".section __ex_table,\"a\"\n"		\
  			PPC_LONG_ALIGN "\n"		\
  			PPC_LONG "1b,4b\n"		\
  			PPC_LONG "2b,4b\n"		\
  		".previous"				\
  		: "=r" (err), "=&r" (x)			\
  		: "b" (addr), "i" (-EFAULT), "0" (err))
  #endif /* __powerpc64__ */
  
  #define __get_user_size(x, ptr, size, retval)			\
  do {								\
  	retval = 0;						\
  	__chk_user_ptr(ptr);					\
  	if (size > sizeof(x))					\
  		(x) = __get_user_bad();				\
  	switch (size) {						\
  	case 1: __get_user_asm(x, ptr, retval, "lbz"); break;	\
  	case 2: __get_user_asm(x, ptr, retval, "lhz"); break;	\
  	case 4: __get_user_asm(x, ptr, retval, "lwz"); break;	\
  	case 8: __get_user_asm2(x, ptr, retval);  break;	\
  	default: (x) = __get_user_bad();			\
  	}							\
  } while (0)
  
  #define __get_user_nocheck(x, ptr, size)			\
  ({								\
  	long __gu_err;						\
  	unsigned long __gu_val;					\
  	__typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
  	__chk_user_ptr(ptr);					\
  	if (!is_kernel_addr((unsigned long)__gu_addr))		\
  		might_fault();					\
  	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
  	(x) = (__typeof__(*(ptr)))__gu_val;			\
  	__gu_err;						\
  })
  
  #define __get_user_check(x, ptr, size)					\
  ({									\
  	long __gu_err = -EFAULT;					\
  	unsigned long  __gu_val = 0;					\
  	__typeof__(*(ptr)) __user *__gu_addr = (ptr);		\
  	might_fault();							\
  	if (access_ok(VERIFY_READ, __gu_addr, (size)))			\
  		__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
  	(x) = (__force __typeof__(*(ptr)))__gu_val;				\
  	__gu_err;							\
  })
  
  #define __get_user_nosleep(x, ptr, size)			\
  ({								\
  	long __gu_err;						\
  	unsigned long __gu_val;					\
  	__typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
  	__chk_user_ptr(ptr);					\
  	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
  	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
  	__gu_err;						\
  })
  
  
  /* more complex routines */
  
  extern unsigned long __copy_tofrom_user(void __user *to,
  		const void __user *from, unsigned long size);
  
  #ifndef __powerpc64__
  
  static inline unsigned long copy_from_user(void *to,
  		const void __user *from, unsigned long n)
  {
  	unsigned long over;
  
  	if (access_ok(VERIFY_READ, from, n))
  		return __copy_tofrom_user((__force void __user *)to, from, n);
  	if ((unsigned long)from < TASK_SIZE) {
  		over = (unsigned long)from + n - TASK_SIZE;
  		return __copy_tofrom_user((__force void __user *)to, from,
  				n - over) + over;
  	}
  	return n;
  }
  
  static inline unsigned long copy_to_user(void __user *to,
  		const void *from, unsigned long n)
  {
  	unsigned long over;
  
  	if (access_ok(VERIFY_WRITE, to, n))
  		return __copy_tofrom_user(to, (__force void __user *)from, n);
  	if ((unsigned long)to < TASK_SIZE) {
  		over = (unsigned long)to + n - TASK_SIZE;
  		return __copy_tofrom_user(to, (__force void __user *)from,
  				n - over) + over;
  	}
  	return n;
  }
  
  #else /* __powerpc64__ */
  
  #define __copy_in_user(to, from, size) \
  	__copy_tofrom_user((to), (from), (size))
  
  extern unsigned long copy_from_user(void *to, const void __user *from,
  				    unsigned long n);
  extern unsigned long copy_to_user(void __user *to, const void *from,
  				  unsigned long n);
  extern unsigned long copy_in_user(void __user *to, const void __user *from,
  				  unsigned long n);
  
  #endif /* __powerpc64__ */
  
  static inline unsigned long __copy_from_user_inatomic(void *to,
  		const void __user *from, unsigned long n)
  {
  	if (__builtin_constant_p(n) && (n <= 8)) {
  		unsigned long ret = 1;
  
  		switch (n) {
  		case 1:
  			__get_user_size(*(u8 *)to, from, 1, ret);
  			break;
  		case 2:
  			__get_user_size(*(u16 *)to, from, 2, ret);
  			break;
  		case 4:
  			__get_user_size(*(u32 *)to, from, 4, ret);
  			break;
  		case 8:
  			__get_user_size(*(u64 *)to, from, 8, ret);
  			break;
  		}
  		if (ret == 0)
  			return 0;
  	}
  	return __copy_tofrom_user((__force void __user *)to, from, n);
  }
  
  static inline unsigned long __copy_to_user_inatomic(void __user *to,
  		const void *from, unsigned long n)
  {
  	if (__builtin_constant_p(n) && (n <= 8)) {
  		unsigned long ret = 1;
  
  		switch (n) {
  		case 1:
  			__put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret);
  			break;
  		case 2:
  			__put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret);
  			break;
  		case 4:
  			__put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret);
  			break;
  		case 8:
  			__put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret);
  			break;
  		}
  		if (ret == 0)
  			return 0;
  	}
  	return __copy_tofrom_user(to, (__force const void __user *)from, n);
  }
  
  static inline unsigned long __copy_from_user(void *to,
  		const void __user *from, unsigned long size)
  {
  	might_fault();
  	return __copy_from_user_inatomic(to, from, size);
  }
  
  static inline unsigned long __copy_to_user(void __user *to,
  		const void *from, unsigned long size)
  {
  	might_fault();
  	return __copy_to_user_inatomic(to, from, size);
  }
  
  extern unsigned long __clear_user(void __user *addr, unsigned long size);
  
  static inline unsigned long clear_user(void __user *addr, unsigned long size)
  {
  	might_fault();
  	if (likely(access_ok(VERIFY_WRITE, addr, size)))
  		return __clear_user(addr, size);
  	if ((unsigned long)addr < TASK_SIZE) {
  		unsigned long over = (unsigned long)addr + size - TASK_SIZE;
  		return __clear_user(addr, size - over) + over;
  	}
  	return size;
  }
  
  extern long strncpy_from_user(char *dst, const char __user *src, long count);
  extern __must_check long strlen_user(const char __user *str);
  extern __must_check long strnlen_user(const char __user *str, long n);
  
  #endif  /* __ASSEMBLY__ */
  #endif /* __KERNEL__ */
  
  #endif	/* _ARCH_POWERPC_UACCESS_H */
  